This invention relates to a filter for liquids, particularly fuel. Such a filter is known, for instance, from DE 43 44 586 A1. This filter comprises a housing having a raw fluid inlet and a purified fluid outlet. A suitable filter element is arranged inside the housing. The prior art filter element furthermore has a collecting cup for dirt and foreign fluids.
A drawback of this system is that when the filter element is replaced, the collecting cup or collecting chamber has to be emptied and cleaned. In addition, a plurality of components is required for effective filtering of the liquids.
It is an object of the invention to provide a liquid filter which avoids or overcomes the aforementioned drawbacks.
Another object of the invention is to provide a liquid filter which is simple in design and achieves high filter performance with few components.
A further object of the invention is to provide a liquid filter which is easy to service.
These and other objects have been achieved in accordance with the present invention by providing a filter for liquids comprising a concentric housing, an unfiltered liquid inlet, a filtered liquid outlet, and a return pipe, wherein a concentric filter element is arranged inside the housing, the housing is sealed with a cover, the housing contains a riser pipe having a return bore in an uppermost part thereof as well as a return pipe, an intermediate pipe that is securely connected to the cover extends above the riser pipe, the filter element is removably arranged on the intermediate pipe, and the filter element has a dirt collecting chamber in a lowermost part thereof.
A significant advantage of the invention is that a riser pipe is provided within the filter housing. Said riser pipe is permanently connected with the housing. Inside the housing there is a return pipe through which on the one hand air can escape when the filter is being ventilated and on the other hand the raw fluid can flow back into the tank. The return pipe is provided with a small bore in the geodesically upper part thereof and is open toward the raw fluid area. An intermediate pipe extends above the riser pipe. Said intermediate pipe is securely latched to the cover and in the geodesically lower part is sealingly connected with the riser pipe. This means that the purified liquid initially rises and then flows through outlet bores into a riser pipe channel and from there reaches the purified liquid outlet. The filter element, which is removably arranged on the intermediate pipe, has a dirt collecting chamber in the geodesically lower part thereof. Said chamber retains any foreign liquid and any dirt particles. When the filter element is replaced, the foreign liquid is simultaneously removed from the filter element.
In accordance with a further embodiment of the invention, a water collecting chamber is provided on the filter element in the geodesically lower part thereof. Its capacity is selected such that the amount of water collected between two service intervals can be stored.
According to a still further embodiment of the invention, the water collecting chamber or dirt collecting chamber is provided with a radially outwardly extending stripper. This stripper contacts the interior wall of the housing and thereby effectively prevents dirt from being deposited in the lower part of the housing. When the filter element is replaced, said water collecting chamber brushes upwardly along the housing wall and removes any dirt particles adhering thereto toward the exterior.
In yet another embodiment of the invention, a valve is arranged in the lower part of the housing. When the housing is open, i.e., when a filter element is being removed, this valve connects the raw fluid area with the return flow area so that the raw fluid can escape from the filter system.
A still further embodiment of the invention comprises an arrangement of support ribs on the cover of the system. These support ribs, which are arranged radially or concentrically, serve to situate the filter element in its correct position. A profile gasket provides the seal between cover and housing. Said profile gasket has a bevel facing the end face of the housing, while the end face of the housing is provided with a counter bevel. One advantage of this sealing principle is that it does not cause any losses through leakage even if the fluid pressure is high.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.